ABSTRACT
The embryonic origin and fetal development of the skeleton are seldom considered in comparative histological literature, although they represent fundamental aspects of skeletal biology. The nature, migration and subsequent differentiation of the initial cell populations contributing to the local development of bones are key elements for understanding local skeletal structure, its dynamics and its diversity in a broad comparative perspective. This chapter summarizes the main stages of skeletal organogenesis. Its scope ranges from the end of gastrulation to birth, with emphasis on the origin, spreading and ultimate fate of the ectodermal and mesodermal mesenchymal cells involved in bone formation. The histogenetic pathways in dermal and endochondral ossification processes, along with their local regulation, are described, and the developmental pattern of the cranial, axial, thoracic and appendicular parts of the skeleton are presented.
